Semiconductor package with chamfered corners and related methods

ABSTRACT

Implementations of image sensors may include a die having either a rounded corner or a chamfered corner edge, and an optically transmissive cover coupled to the die. The optically transmissive cover may include either a rounded corner or a chamfered corner edge that corresponds with either the rounded corner or the chamfered corner edge of the die.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of the earlier U.S.Utility patent application to Oswald Skeete entitled “SemiconductorPackage with Chamfered Corners and Related Methods,” application Ser.No. 15/892,114, filed Feb. 8, 2018, the disclosure of which is herebyincorporated entirely herein by reference.

BACKGROUND 1. Technical Field

Aspects of this document relate generally to image sensors, such as chipscale image sensors. More specific implementations involve image sensorswith rounded or chamfered corners.

2. Background

A chip scale package (CSP) is designed to be the same size as, or nearlythe same size as, the semiconductor die (chip) itself. Various CSPpackages include various types of semiconductor die, including imagesensors. Image sensors convey information related to an image bycommunicating signals in response to incident electromagnetic radiation.Image sensors are used in a variety of devices including smart phones,digital cameras, night vision devices, medical imagers, and many others.

SUMMARY

Implementations of image sensors may include a die having either arounded corner or a chamfered corner edge, and an optically transmissivecover coupled to the die. The optically transmissive cover may includeeither a rounded corner or a chamfered corner edge that corresponds witheither the rounded corner or the chamfered corner edge of the die.

Implementations of image sensors may include one, all, or any of thefollowing:

The corners of the die may be convexly rounded.

The corners of the die may be concavely rounded.

The optically transmissive cover may include glass.

Either the rounded corner or the chamfered corner edge of the die may beformed through etching.

Implementations of a method for forming an image sensor device mayinclude forming a first plurality of openings in an opticallytransmissive cover, coupling the optically transmissive cover to a wafercomprising a plurality of image sensors, etching a second plurality ofopenings through the wafer, the second plurality of openings aligningwith the first plurality of openings in the optically transmissivecover, and singulating the optically transmissive cover and the waferinto a plurality of image sensor devices. Each image sensor device mayinclude either a rounded corner or a chamfered corner edge.

Implementations of image sensors may include one, all, or any of thefollowing:

Etching one or more through-silicon-vias while etching the secondplurality of openings through the wafer.

Each opening of the first plurality of openings may include a perimeterin a closed four-sided shape.

Each opening of the first plurality of openings may include a perimeterin a circular shape.

Each opening of the first plurality of openings may include a perimeterin an elliptical shape.

The optically transmissive cover may include glass.

The first plurality of openings may be formed through etching.

The method may include aligning the first plurality of openings of theoptically transmissive cover with a plurality of corners of theplurality of image sensors.

The method may include etching the second plurality of holes through thewafer while using the optically transmissive cover as a guide.

Implementations of a method for forming an image sensor device mayinclude forming a first plurality of openings in an opticallytransmissive cover, coupling the optically transmissive cover to a waferincluding a plurality of image sensors, using the optically transmissivecover as a guide, etching a second plurality of openings through thewafer, and singulating the optically transmissive cover and the waferinto a plurality of image sensor devices. Each image sensor device mayinclude either a rounded corner or a chamfered corner edge.

Implementations of image sensors may include one, all, or any of thefollowing:

Each opening of the first plurality of openings may include a perimeterin a closed four-sided shape.

Each opening of the first plurality of openings may include a perimeterin a circular shape.

Each opening of the first plurality of openings may include a perimeterin an elliptical shape.

The optically transmissive cover may include glass.

The second plurality of openings may be formed through a deep reactiveion etching process.

The foregoing and other aspects, features, and advantages will beapparent to those artisans of ordinary skill in the art from theDESCRIPTION and DRAWINGS, and from the CLAIMS.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations will hereinafter be described in conjunction with theappended drawings, where like designations denote like elements, and:

FIG. 1 is a top view of an image sensor with rounded corners;

FIG. 2 is a top view of an image sensor with chamfered corner edges;

FIG. 3 is a top view of an image sensor with right-angled corners;

FIG. 4 is a top view of a cover;

FIG. 5 is a top view of the cover of FIG. 4 with openings formedtherein;

FIG. 6 is a top view of a wafer;

FIG. 7 is a top view of the cover of FIG. 5 aligned over the wafer ofFIG. 6; and

FIG. 8 is a top view of four die after the wafer and cover of FIG. 7 hasbeen singulated.

DESCRIPTION

This disclosure, its aspects and implementations, are not limited to thespecific components, assembly procedures or method elements disclosedherein. Many additional components, assembly procedures and/or methodelements known in the art consistent with the intended semiconductorpackages will become apparent for use with particular implementationsfrom this disclosure. Accordingly, for example, although particularimplementations are disclosed, such implementations and implementingcomponents may comprise any shape, size, style, type, model, version,measurement, concentration, material, quantity, method element, step,and/or the like as is known in the art for such semiconductor packages,and implementing components and methods, consistent with the intendedoperation and methods.

Referring to FIG. 1, a top view of an image sensor with rounded cornersis illustrated. The image sensors disclosed herein may be chip scaleimage sensors or any other image sensor known to those of ordinary skillin the art. Also, the principles disclosed herein may be applied to moresemiconductor packages and device types than image sensors, including,by non-limiting example, processors, power devices, discrete components,and any other device formed on a semiconductor substrate. As illustratedby FIG. 1, the image sensor 2 includes a die 4 that includes a pixelarray 6. In various implementations, the image sensor may also includerounded corners 8. The rounded corners may vary in size from very smallrounded corners on an basically rectangular die, to very large roundedcorners that make the image sensor die nearly circular. In theimplementation illustrated by FIG. 1, the rounded corners 8 are convexrounded corners, however, in other implementations, the rounded cornersmay be concave rounded corners with the arc of the corner extendingtowards the center of the die rather than away from the die.

In various implementations, the image sensor 2 may include an opticallytransmissive cover 10 coupled to the die 4. In various implementationsthe optically transmissive cover 10 is coupled directly to the die,however, in other implementations there may be various elements betweenthe die 4 and the optically transmissive cover 10. In variousimplementations the optically transmissive cover is coupled to the diethrough an adhesive or other bonding material. The adhesive may bond theedges 12 of the die 4 to the edges 14 of the optically transmissivecover 10. The optically transmissive cover 10 may be opticallytransparent or optically translucent. In particular implementations, theoptically transmissive cover 10 may be, by non-limiting example, glass,sapphire, or any other optically transmissive material. The opticallytransmissive cover 10 may include corners 16 that correspond to thecorners of the die 4. As is the case illustrated by FIG. 1, the cornersof the optically transmissive cover 16 may be convexly rounded, thoughin other implementations, the corners may be concavely rounded.

An optical element 18, such as a lens holder, may be also coupled to theimage sensor 2. The optical element 18 may be circular, as is often thecase with optical elements added to image sensors that make up a fullcamera system. As illustrated by FIG. 1, the perimeter of the imagesensor 2 fits within the circular optical element 18.

Referring to FIG. 2, a top view of an image sensor with chamfered corneredges is illustrated. The image sensor 20 of FIG. 2 is essentially thesame as the image sensor 2 of FIG. 1, with the exception that ratherthan having rounded corners, the image sensor 20, including the die 22and the optically transmissive cover, has chamfered corner edges 24. Thelength of the chamfered corner edges may vary. As illustrated by FIG. 2,a perimeter of the image sensor 20 is configured to fit within acircular optical element 26, similar to the image sensor 2 of FIG. 1.

Referring to FIG. 3, a top view of an image sensor with right-anglecorners is illustrated. The image sensor 28 of FIG. 3 is similar to theimage sensors of FIGS. 1 and 2, with the difference being that thecorners 30 of the image sensor are not rounded or chamfered. As aresult, the image sensor 28 is not able to fit within the opticalelement 32 because the corners 30 have right angles. Contrary to this,the image sensors of FIGS. 1-2 are able to fit within their respectiveoptical elements due to the rounded or chamfered corners. As a result,the image sensors of FIGS. 1-2, which have the same sized pixel array asthe pixel array 32 of FIG. 3, are able to fit within a smaller opticalelement, thus reducing the overall size of the camera system withoutcompromising the quality or performance of the image sensor. This is inpart because the material of the die at the corners generally does notinclude components needed to operate the image sensor and so representsextra material in various implementations.

The implementations illustrated by FIGS. 1-3 have optical elementsillustrated as the same size and image sensors also illustrated asessentially the same size, with the only difference being that the edgesof the image sensors of FIGS. 1-2 are respectively rounded andchamfered. In various implementations, the dimensions of the imagesensor and/or optical elements may vary. In one example of a particularimplementation, the diameter of the optical element may be substantially7.5 millimeters (mm). The length of the image sensor may besubstantially 5.7 mm, and the perimeter of the image sensor may be asquare. The length of each side of the pixel array may be substantially5 mm, and the length between the edge of the image sensor and the edgeof the pixel array may be substantially 0.25 mm.

Referring to FIGS. 4-8, a process for forming the image sensor of FIG. 1or FIG. 2 is illustrated. Referring specifically to FIG. 4, a top viewof a cover is illustrated. The method of forming an image sensorincludes providing a cover, and the cover may be an opticallytransmissive cover 36. In various implementations, the opticallytransmissive cover is optically transparent, while in otherimplementations the optically transmissive cover is opticallytranslucent. In various implementations, the optically transmissivecover 36 may be, by non-limiting example, glass, sapphire, or any otheroptically transmissive material. While the optically transmissive coveris illustrated as being circular in FIG. 4, in various implementationsthe cover may be other shapes.

Referring to FIG. 5, a top view of the cover of FIG. 4 with openingsformed therein is illustrated. The method of forming an image sensor mayinclude forming a first plurality of openings 38 in the transmissivecover 36. In various implementations, a width of the openings may besubstantially 0.5 mm, however, in other implementations the width of theopenings may be more or less than 0.5 mm. As illustrated by FIG. 5, invarious implementations each opening of the first plurality of openingsincludes a perimeter in, by non-limiting example, a closed four-sidedshape, a circular shape, or an elliptical shape. By non-limitingexample, the closed four-sided shape may include a rhombus, such as asquare or diamond, a rectangle, or any other quadrilateral. Further, theclosed four-sided shape of the perimeter of the opening may include arhombus, such as a diamond, with curved concave edges. In variousimplementations, and as illustrated by FIG. 5, not each of the openingswithin the first plurality of openings 38 is formed entirely within theoptically transmissive cover 36. In particular implementations, openings40 of the plurality of openings 38 formed on the edge of the opticallytransmissive cover may form an opening partially within the perimeter ofthe optically transmissive cover 36. To illustrate this point in FIG. 5,the perimeter of the openings that extend across the perimeter of thecover 36 is shown, though in actual fact the edge of the openings acrossthe perimeter would not actually exist. The number of openings withinthe first plurality of openings 36, as well as the spacing between theopenings of the first plurality of openings may depend on the number andpositioning of corners of a plurality of die containing image sensingelements, as explained later herein. In particular implementations, thefirst plurality of openings 38 may be etched through the opticallytransmissive cover. In such implementations, the openings may be formedusing, by non-limiting example, plasma etching, deep-reactive ionetching, or wet chemical etching. In various implementations, a processmarketed under the tradename BOSCH® by Robert Bosch GmbH, StuttgartGermany (the “Bosch process”), may be used to form the first pluralityof openings 38 in the optically transmissive cover 36.

Referring to FIG. 6, a top view of a wafer is illustrated. The methodfor forming the image sensor includes providing a wafer 42 including aplurality of die 44. Each die of the plurality of die 44 may includeimage sensing elements, such as a pixel array. In variousimplementations, the plurality of die 44 may be any disclosed in thisdocument. In various implementations, a perimeter of each die may berectangular or a square. In other implementations, the perimeter of eachdie within the plurality of dies 44 may be a different shape andcorrespondingly, the shape of the openings in the cover may be variedaccording to the perimeter of each die.

Referring to FIG. 7, a top view of the cover of FIG. 5 aligned over thewafer of FIG. 6 is illustrated. The method for forming the image sensorincludes aligning the first plurality of openings 38 of the opticallytransmissive cover 36 with a plurality of corners 46 of the plurality ofdie 44. As illustrated by FIG. 7, in implementations where a corner of adie is adjacent to three other corners of three other die, a singlerespective opening in the optically transmissive cover is aligned tocover the corner of each of the four adjacent die. The opticallytransmissive cover 36 may be aligned with the wafer 42 using variousalignment techniques, including, by non-limiting example, notchalignment of the optically transmissive cover with the wafer, opticalalignment using alignment features on the wafer, optical alignment usingthe shapes of the plurality of openings and the streets of the die onthe wafer, any combination thereof, and any other method of ensuring theopenings are aligned over the corners of the die.

The method of forming an image sensor may include coupling the opticallytransmissive cover 36 to the wafer 42 having the plurality of die 44. Invarious implementations, the optically transmissive cover 36 may becoupled to the wafer 42 using an adhesive or bonding material. In suchimplementations, the adhesive may be applied between the wafer 42 andthe optically transmissive cover 36 in specific locations so as to notinterfere with the pixel array.

The method for forming an image sensor includes forming a secondplurality of openings through the wafer 42. The second plurality ofopenings correspond in shape, size, and location, to the first pluralityof openings 38, and as a result, are formed at the plurality of corners46 of each die of the plurality of die 44. In various implementations,the second plurality of openings may be etched through the wafer 42using any etching technique previously disclosed herein. In particularimplementations, the optically transmissive cover 36 may be used as aguide to etch the second plurality of openings through the die. In suchimplementations, the method may include coupling a mask (notillustrated) to the optically transmissive cover 36. The mask may beformed using various lithographic processes or formed from applicationof a film followed by patterning or application of a patterned film overthe optically transmissive cover 36. The mask has a plurality ofopenings that correspond with the first plurality of openings 38. Theoptically transmissive cover may be considered a guide as it dictateswhere the openings in the mask are located and the openings in the waferare formed. The mask may be coupled to the optically transmissive coverin order to prevent additional etching or damage to the opticallytransmissive cover 36. The second plurality of openings may be formedthrough the wafer 42 using the mask coupled to the opticallytransmissive cover. This method may ensure that the first plurality ofopenings 38 and the second plurality of openings correspond. In otherimplementations, the optically transmissive cover may be used as themask without covering it with a masking material. In still otherimplementations, the second plurality of openings may be partially orentirely formed or etched from the side of the wafer 42 opposite theside of the wafer coupled to the optically transmissive cover 36. Invarious implementations, the etching of the wafer 42 may be timed usingto the etch rate of the silicon or other wafer material to ensure thatthe etch of the wafer 42 does not significantly continue to etch theoptically transmissive cover 36.

In other implementations, the method of forming the image sensor mayinclude coupling an optically transmissive cover without any openings toa wafer. In such implementations, the method may include forming a maskover the optically transmissive cover with a plurality of openingstherein which align with the plurality of corners of the plurality ofdie in the wafer. The method may include etching through both theoptically transmissive cover and the wafer using the mask coupled to theoptically transmissive cover.

In various implementations, the method of forming the image sensor mayinclude performing other procedures, like forming (or etching)through-silicon-vias (TSV) in the wafer followed by forming aredistribution layer (RDL) and solder balls or bumps used to couple theimage sensor to an external device. Such procedures may be performed atthe same time the second plurality of openings are formed through thewafer 42. In particular implementations, the TSVs and the secondplurality of openings may be simultaneously formed through a wet etchprocess.

Referring to FIG. 8, a top view of four image sensor devices after thewafer and the cover of FIG. 7 have been singulated is illustrated. Themethod for forming the image sensor includes singulating the opticallytransmissive cover and the wafer into a plurality of image sensordevices 48. The singulation may take place using, by non-limitingexample, saw cutting, laser cutting, water cutting, any combinationthereof, and any other method of cutting the material of the coverand/or wafer. As illustrated by FIG. 8, each image sensor device of theplurality of image sensor device 48 includes a plurality of chamferedcorner edges. The chamfered corner edges may be the result of formingquadrilateral, or diamond shaped, openings over the corners of each dieof the plurality of die of the wafer. In other implementations, thesingulated image sensor devices 48 may each have rounded corners,similar to the image sensor of FIG. 1. In such implementations, thefirst plurality of openings 36 of the optically transmissive cover mayhave included openings with a perimeter in a diamond shape havingconcave edges in order to form the convex rounded corners (similar tothe corners of FIG. 1). Alternatively, the first plurality of openings36 of the optically transmissive cover may have included openings with aperimeter in the shape of a circle or an ellipse in order to formconcave rounded corners of the image sensors.

In various implementations, the wafer 42 and optically transmissivecover 36 are singulated using a saw. In such implementations, the widthof the saw blade is less than the width of each opening of the first orsecond plurality of openings. In this manner, the corners of each diemay be rounded or chamfered. In other implementations, the wafer issingulated using, by non-limiting example, a laser, water jet, or othersingulation device.

By rounding or chamfering the corners of the die and the cover of theimage sensor, the image sensor is able to fit within smaller opticalelements, such as a lens holder, which is often circular. This methodmay allow for an overall smaller camera system without having todecrease the size of the pixel array or sacrifice image quality inexchange for a smaller camera system. Further, many optical elements,such as lens holders, vary slightly in size, thus the image sensors willalso need to vary slightly in size to accommodate the various sizes ofoptical elements. By altering the size of the openings in the cover andthe die while forming the image sensor, different sized image sensorsmay be produced easily without having to manufacture different siliconwafers. The width of the saw blade singulating the image sensors mayalso be varied to alter the size of the image sensors without having tomanufacture different silicon wafers.

Though this application primarily focuses on the structure of an imagesensor and the method for forming the image sensor, the methodsdisclosed herein may be applied to other semiconductor devices which arenot image sensors. In various implementations, rather than having anoptically transmissive cover coupled to the wafer, a cover that is notoptically transmissive may be coupled to a wafer that includes aplurality of die. In such implementations, the cover may be a metallayer, another wafer, a semiconductor material, or another materialformed into a planar layer, which may or may not have the same perimeteras the wafer. In other implementations, rather than the device having acover, the methods and techniques disclosed herein may apply to theformation of stacked/bonding die. In such implementations, a first wafercomprising a plurality of die may have a plurality of openings etchedtherethrough. The first wafer may then be coupled to a second wafer alsoincluding a plurality of die, and a corresponding set of openings may beformed through the second wafer. The corresponding set of openings maybe etched through the second wafer, and the first wafer may be used as aguide during the etching. Such methods and techniques may be employed informing micro-electro-mechanical systems (MEMS) where the MEMS device isbonded to a second wafer which contains control or sensors that interactwith the MEMS device.

In places where the description above refers to particularimplementations of image sensors and implementing components,sub-components, methods and sub-methods, it should be readily apparentthat a number of modifications may be made without departing from thespirit thereof and that these implementations, implementing components,sub-components, methods and sub-methods may be applied to other imagesensors.

What is claimed is:
 1. An image sensor comprising: a die comprising a rounded corner or a chamfered corner edge; and an optically transmissive cover coupled to the die; wherein a perimeter of the optically transmissive cover is aligned with a perimeter of the die; and wherein the perimeter of the optically transmissive cover is not set in from the perimeter of the die.
 2. The image sensor of claim 1, wherein the rounded corner or the chamfered corner edge of the die is convexly rounded.
 3. The image sensor of claim 1, wherein the rounded corner or the chamfered corner edge of the die is concavely rounded.
 4. The image sensor of claim 1, wherein the optically transmissive cover comprises glass.
 5. The image sensor of claim 1, wherein the rounded corner or the chamfered corner edge of the die are formed through etching.
 6. The image sensor of claim 1, wherein two or more sidewalls of the optically transmissive cover are aligned with two or more sidewalls of the die.
 7. An image sensor comprising: a die comprising a rounded corner or a chamfered corner edge; and an optically transmissive cover coupled to the die; wherein the optically transmissive cover comprises a rounded corner or a chamfered corner edge; wherein a perimeter of the optically transmissive cover is substantially the same size as a perimeter of the die; and wherein the rounded corner or the chamfered corner edge of the optically transmissive cover is not set in from the rounded corner or the chamfered corner edge of the die.
 8. The image sensor of claim 7, wherein the rounded corner or the chamfered corner edge of the die is convexly rounded.
 9. The image sensor of claim 7, wherein the rounded corner or the chamfered corner edge of the die is concavely rounded.
 10. The image sensor of claim 7, wherein the optically transmissive cover comprises glass.
 11. The image sensor of claim 7, wherein the rounded corner or the chamfered corner edge of the die are formed through etching.
 12. An image sensor comprising: a die comprising a rounded corner or a chamfered corner edge; and an optically transmissive cover coupled to the die; wherein the optically transmissive cover comprises a rounded corner or a chamfered corner edge; and wherein the rounded corner or the chamfered corner edge of the optically transmissive cover is not set in from the rounded corner or the chamfered corner edge of the die.
 13. The image sensor of claim 12, wherein the rounded corner or the chamfered corner edge of the die is convexly rounded.
 14. The image sensor of claim 12, wherein the rounded corner or the chamfered corner edge of the die is concavely rounded.
 15. The image sensor of claim 12, wherein the optically transmissive cover comprises glass.
 16. The image sensor of claim 12, wherein the rounded corner or the chamfered corner edge of the die are formed through etching.
 17. The image sensor of claim 12, wherein the rounded corner or the chamfered corner edge of the optically transmissive cover lines up with the rounded corner or the chamfered corner edge of the die. 